1. Field of the Invention
The present invention relates to a magnetic garnet single crystal film, a method for manufacturing the magnetic garnet single crystal film, and a magnetostatic wave device having the magnetic garnet single crystal film, and more particularly to magnetic garnet single crystal film and the like which are used for a magnetostatic wave device such as a limiter, a noise filter, or the like.
2. Description of the Related Art
A Y3Fe5O12 (YIG) single crystal film is an important substance used as a magnetic garnet single crystal film for a magnetostatic wave device. Particularly, the YIG single crystal film is excellent due to an extremely narrow ferromagnetic half-width (xcex94H). When the YIG single crystal film is applied to the magnetostatic wave device, this characteristic can make the difference between an input signal and an output signal small. Furthermore, another characteristic of the YIG single crystal film is that a saturation phenomenon occurs at a relatively small electric power compared with the input signal. The YIG single crystal film is widely used for magnetostatic wave devices such as a limiter and a noise filter which utilize the aforementioned characteristics.
A magnetic garnet single crystal film including a Fe element other than the YIG single crystal film is also applied to the magnetostatic wave device in a manner similar to that of the YIG single crystal film.
Although the magnetic garnet single crystal film has the excellent properties as explained above, the conventional magnetic garnet single crystal film also has the drawbacks. Specifically, a large insertion loss, long transient response time, and high saturated input power impair the aforementioned properties in applying the magnetic garnet single crystal film to magnetostatic wave devices. These characteristics are especially important for microwave device use.
It is therefore an object of the present invention to provide a magnetic garnet single crystal film which can produce a higher performance magnetostatic wave device.
Another object of the present invention is to provide a method for manufacturing the magnetic garnet single crystal film which can produce the higher performance magnetostatic wave device.
Further object of the present invention is to provide a higher performance magnetostatic wave device.
The magnetic garnet single crystal film used for a magnetostatic wave device, according to the present invention, contains Pb in the range from more than zero to not more than about 4,000 ppm by weight. The method for manufacturing the magnetic garnet single crystal film in accordance with the present invention comprises the step of growing the magnetic garnet single crystal film by liquid phase epitaxy using a PbO-based flux at a temperature of not less than about 940xc2x0 C. Alternatively, the growing step may be performed by liquid phase epitaxy using a PbO-based flux having a content of a Pb compound of not more than about 70 percent by weight in terms of PbO content.
The magnetostatic wave device in accordance with the present invention includes Pb at a content of more than zero and not more than about 4,000 ppm by weight.
Thus, the present invention makes it possible to prevent insertion loss, and increases transient response time and saturated input electrical power with respect to a magnetostatic wave device using the magnetic garnet single crystal film.
For the purpose of illustrating the invention, there is shown in the drawing a form which is presently preferred, it being understood, however, that the invention is not limited to the precise arrangement and instrumentality shown.